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Authors:Finck B. N.Pages: 2485 - 2493Abstract: Obesity, insulin resistance, and diabetes are strongly linked to the accumulation of excessive lipids in the liver parenchyma, a condition known as nonalcoholic fatty liver disease (NAFLD). Given its association with obesity and related metabolic diseases, it is not surprising that the prevalence of NAFLD has dramatically increased in the past few decades. NAFLD has become the most common liver disease in many areas of the world. The term, NAFLD, encompasses a spectrum of disorders that ranges from simple steatosis to steatosis with inflammatory lesions (nonalcoholic steatohepatitis [NASH]). Although simple steatosis might be relatively benign, epidemiologic studies have linked NASH to greatly increased risk of developing cirrhosis and hepatocellular carcinoma. Yet despite this, there are no approved treatments for the disease, and it remains a significant unmet medical need. This Perspective will review some of the relevant literature on the topic and examine approved and experimental NASH therapeutic concepts that target intermediary metabolism, insulin resistance, and diabetes to treat this emerging public health problem.Keywords: Integrated Physiology-LiverPubDate: 2018-11-20T12:00:29-08:00DOI: 10.2337/dbi18-0024Issue No:Vol. 67, No. 12 (2018)

Authors:
Faber; C. L.; Matsen, M. E.; Velasco, K. R.; Damian, V.; Phan, B. A.; Adam, D.; Therattil, A.; Schwartz, M. W.; Morton, G. J.Pages: 2518 - 2529Abstract: The hypothalamic ventromedial nucleus (VMN) is implicated both in autonomic control of blood glucose and in behaviors including fear and aggression, but whether these divergent effects involve the same or distinct neuronal subsets and their projections is unknown. To address this question, we used an optogenetic approach to selectively activate the subset of VMN neurons that express neuronal nitric oxide synthase 1 (VMNNOS1 neurons) implicated in glucose counterregulation. We found that photoactivation of these neurons elicits 1) robust hyperglycemia achieved by activation of counterregulatory responses usually reserved for the physiological response to hypoglycemia and 2) defensive immobility behavior. Moreover, we show that the glucagon, but not corticosterone, response to insulin-induced hypoglycemia is blunted by photoinhibition of the same neurons. To investigate the neurocircuitry by which VMNNOS1 neurons mediate these effects, and to determine whether these diverse effects are dissociable from one another, we activated downstream VMNNOS1 projections in either the anterior bed nucleus of the stria terminalis (aBNST) or the periaqueductal gray (PAG). Whereas glycemic responses are fully recapitulated by activation of VMNNOS1 projections to the aBNST, freezing immobility occurred only upon activation of VMNNOS1 terminals in the PAG. These findings support previous evidence of a VMN->aBNST neurocircuit involved in glucose counterregulation and demonstrate that activation of VMNNOS1 neuronal projections supplying the PAG robustly elicits defensive behaviors.Keywords: Integrated Physiology-Central Nervous System Regulation of MetabolismPubDate: 2018-11-20T12:00:29-08:00DOI: 10.2337/db18-0380Issue No:Vol. 67, No. 12 (2018)

Authors:
Stanford; K. I.; Rasmussen, M.; Baer, L. A.; Lehnig, A. C.; Rowland, L. A.; White, J. D.; So, K.; De Sousa-Coelho, A. L.; Hirshman, M. F.; Patti, M.-E.; Rando, O. J.; Goodyear, L. J.Pages: 2530 - 2540Abstract: Poor paternal diet has emerged as a risk factor for metabolic disease in offspring, and alterations in sperm may be a major mechanism mediating these detrimental effects of diet. Although exercise in the general population is known to improve health, the effects of paternal exercise on sperm and offspring metabolic health are largely unknown. Here, we studied 7-week-old C57BL/6 male mice fed a chow or high-fat diet and housed either in static cages (sedentary) or cages with attached running wheels (exercise trained). After 3 weeks, one cohort of males was sacrificed and cauda sperm obtained, while the other cohort was bred with chow-fed sedentary C57BL/6 females. Offspring were chow fed, sedentary, and studied during the first year of life. We found that high-fat feeding of sires impairs glucose tolerance and increases the percentage of fat mass in both male and female offspring at 52 weeks of age. Strikingly, paternal exercise suppresses the effects of paternal high-fat diet on offspring, reversing the observed impairment in glucose tolerance, percentage of fat mass, and glucose uptake in skeletal muscles of the offspring. These changes in offspring phenotype are accompanied by changes in sperm physiology, as, for example, high-fat feeding results in decreased sperm motility, an effect normalized in males subject to exercise training. Deep sequencing of sperm reveals pronounced effects of exercise training on multiple classes of small RNAs, as multiple changes to the sperm RNA payload observed in animals consuming a high-fat diet are suppressed by exercise training. Thus, voluntary exercise training of male mice results in pronounced improvements in the metabolic health of adult male and female offspring. We provide the first in-depth analysis of small RNAs in sperm from exercise-trained males, revealing a marked change in the levels of multiple small RNAs with the potential to alter phenotypes in the next generation.Keywords: ExercisePubDate: 2018-11-20T12:00:29-08:00DOI: 10.2337/db18-0667Issue No:Vol. 67, No. 12 (2018)

Authors:
He; L.; Tang, M.; Xiao, T.; Liu, H.; Liu, W.; Li, G.; Zhang, F.; Xiao, Y.; Zhou, Z.; Liu, F.; Hu, F.Pages: 2585 - 2600Abstract: miRNAs are important regulators of differentiation, development, and function of brown and beige fat cells. In this study, we identify the role of the miR-199a/214 cluster in the regulation of brown and beige adipocyte development and thermogenesis in vitro and in vivo. We show that expression of the miR-199a/214 cluster is dramatically decreased during brown and beige adipocyte differentiation and in response to cold exposure or β-adrenergic receptor activation. The cluster levels are significantly upregulated in the adipose tissues of obese mice and human subjects. Overexpression of the miR-199a/214 cluster suppresses brown adipocyte differentiation and inhibits thermogenic gene expression and mitochondrial respiration, whereas knockdown of the cluster increases thermogenic gene expression and mitochondrial function in beige adipocytes. In addition, inhibition of the miR-199a/214 cluster promotes beiging effects in vivo. We further show that miR-199a/214 suppresses brown adipocyte differentiation and beige fat development by directly targeting PRDM16 and peroxisome PGC-1α, two key transcriptional regulators of adipose browning. Together, these observations reveal that the miR-199a/214 cluster is a key negative regulator of brown and beige fat development and thermogenesis.Keywords: Obesity-AnimalPubDate: 2018-11-20T12:00:29-08:00DOI: 10.2337/db18-0626Issue No:Vol. 67, No. 12 (2018)

Authors:
Tao; W.; Zhang, Y.; Ma, L.; Deng, C.; Duan, H.; Liang, X.; Liao, R.; Lin, S.; Nie, T.; Chen, W.; Wang, C.; Birchmeier, C.; Jia, S.Pages: 2615 - 2625Abstract: Baseline β-cell mass is established during the early postnatal period when β-cells expand. In this study, we show that heterozygous ablation of Insm1 decreases baseline β-cell mass and subsequently impairs glucose tolerance. When exposed to a high-fat diet or on an ob/ob background, glucose intolerance was more severe in Insm1+/lacZ mice compared with Insm1+/+ mice, although no further decrease in the β-cell mass was detected. In islets of early postnatal Insm1+/lacZ mice, the cell cycle was prolonged in β-cells due to downregulation of the cell cycle gene Ccnd1. Although Insm1 had a low affinity for the Ccnd1 promoter compared with other binding sites, binding affinity was strongly dependent on Insm1 levels. We observed dramatically decreased binding of Insm1 to the Ccnd1 promoter after downregulation of Insm1 expression. Furthermore, downregulation of Ccnd1 resulted in a prolonged cell cycle, and overexpression of Ccnd1 rescued cell cycle abnormalities observed in Insm1-deficient β-cells. We conclude that decreases in Insm1 interfere with β-cell specification during the early postnatal period and impair glucose homeostasis during metabolic stress in adults. Insm1 levels are therefore a factor that can influence the development of diabetes.Keywords: Islet Biology-Beta Cell-Development and Postnatal GrowthPubDate: 2018-11-20T12:00:29-08:00DOI: 10.2337/db17-1330Issue No:Vol. 67, No. 12 (2018)

Authors:
Sukumar; N.; Bagias, C.; Goljan, I.; Weldeselassie, Y.; Gharanei, S.; Tan, B. K.; Holst, J. J.; Saravanan, P.Pages: 2650 - 2656Abstract: Glucagon-like peptide 1 (GLP-1) levels may be reduced in type 2 diabetes, but whether a similar impairment exists in gestational diabetes mellitus (GDM) has not been established. We studied this in a prospective cohort study of pregnant women (n = 144) during oral glucose tolerance test (OGTT). GLP-1, glucose, and insulin were sampled at 30-min intervals during a 2-h 75-g OGTT, and indices of insulin secretion and sensitivity were calculated. In a nested case-control study, women with GDM (n = 19) had 12% lower total GLP-1 secretion area under the curve (AUC) compared with control subjects matched for age, ethnicity, and gestational age (n = 19), selected from within the lowest quartile of glucose120 min values in our cohort. GDM had lower GLP-1 response in the first 30 min (19% lower GLP-130 min and 17% lower AUC0–30 min) after adjustment for possible confounders. Their glucose levels began to diverge at 30 min of the OGTT with increasing insulin levels, and by 120 min, their insulin levels were three times higher. In a secondary cohort of 57 women that included "high-normal" glucose120 min values, low GLP-1 AUC0–30 min was independently associated with lower indices of insulin secretion and sensitivity. In conclusion, we have observed that women with GDM have lower GLP-1 response at 30 min of an OGTT and hyperglycemia at 120 min despite significant hyperinsulinemia.Keywords: Pregnancy-Clinical/EpidemiologyPubDate: 2018-11-20T12:00:29-08:00DOI: 10.2337/db18-0254Issue No:Vol. 67, No. 12 (2018)